Latest questions from the community.
SFP+ DACs linked MikroTik-to-MikroTik and OLT-to-OLT, but between a V-SOL EPON OLT 16008D and a CCR2004-1G-12S+2XS or CRS326-24G-2S+RM the OLT reported the interface as disconnected. The same DACs were recognised on both platforms, so the poster suspected a cross-vendor auto-negotiation or…
On a CRS226-24G-S2+RM (RouterOS 6.42.11 long-term) the SFP+ port stayed at no link, not running, slave after a power loss, while software reboots were fine; disabling and re-enabling the interface fixed it manually. The problematic module was a Huawei MA5671A GPON SFP, other SFPs behaved, and the…
After upgrading a CRS305-1G-4S+ to SwOS 2.12, SFP-GE-T 1000BASE-T copper SFPs stopped linking although the switch still identified them in the SFP tab; the same modules kept working on a CRS317-1G-16S+ with the same firmware. Modules inserted before the upgrade continued to work, modules inserted…
On a CRS326-24G-2S+ with RouterOS 7.7 three third-party 1G RJ45 SFPs failed: an HP 453156-001 (FCLF-8521-3-HP) showed no-link with auto-negotiation: failed, a Foundry E1MG-TX showed no-link with sfp-rx-loss: yes even with manual speed, and a Ubiquiti UF-RJ45-1G also stayed at no-link. Hardware…
A MikroTik CCR1036-8G-2S+ with S-31DLC20D 1.25G single-mode SFPs reported link OK but no traffic flowed; TX power was blank and RX was -9 dBm. The identical module on the same fibre worked in a CCR1036-12G-4S. Port disable/enable, forcing 1G full duplex on both ends and support tickets did not…
Two FS.com 1G BiDi SFPs (1490/1310 and 1310/1490 nm) in a MikroTik CRS326-24G-2S+ running SwOS 2.9 detected incoming light around -6 dBm but never established a link; the same optics linked on a Netgear switch. The poster asked whether a manual speed setting was needed and whether RouterOS would…
A first-time SFP+ deployment between a UniFi 16XG switch and a Tehuti Networks TN9310 SFP+ adapter, with transceivers the reseller called compatible, produced an Rx fault indication in the UniFi controller. Swapping the fibre ends (polarity) did not help. Hardware involved: Ubiquiti US-16-XG…
FS.com 40 km 1550 nm SFP+ modules (item 11592) showed their information in a MikroTik CCR1016 but never linked in the SFP+ ports, whatever the auto-negotiation, 1G/10G speed or flow-control settings; standard 10G modules (item 29851) worked in the same ports, and the 40 km modules ran at 1G in…
A MikroTik CSS610-8P-2S+ (SwOS Lite) needed to connect its SFP+ ports to a Cisco Nexus 5596UP. The ports showed the transceivers in the web UI but no link, after trying several fibre cables and transceivers. The switch web UI listed vendor and type for each module, yet the port stayed at no-link…
A pfSense router on a Supermicro R210 II with an AOC-STGN-i2S (82599-based X520 clone) was connected throguh an FS.com SFP+-to-RJ45 module to a cable modem with a 2.5 Gbps port. No link negotiation happened; pfSense offered only auto and 10G speeds and never 2.5G. Hardware involved: Supermicro…
An embedded device with a 10GbE SFP transceiver kept logging power warnings above 800 mW and occasional errors when fed by an NVIDIA/Mellanox MMA2P00-AS 10/25G transceiver over a 2 m OM3 LC patch. The poster assumed transmit power is negotiated between the two ends and asked whether a failed…
Mellanox ConnectX-3 MCX314A-BCBT and MCX354A-FCB cards (firmware 2.42.5000, driver 5.50.14740.1) were detected in Windows 11 and Ubuntu 22.10 but no optical transceiver ever emitted light: Cisco QSFP-40G-SR-BD, Cisco SFP-10G-SR and Mellanox MFM1T02A-SR were tried on LC-LC OM3, aross three…
Used Intel 82599ES 10-Gigabit SFI/SFP+ NICs from eBay were connected with 10Gtek SFP+ DACs and, via QNAP switches, with 10Gtek SR transceivers over OM3. On Linux dmesg looped NIC Link is Up 10 Gbps / NIC Link is Down; on FreeBSD the interface showed no carrier and DHCP failed. allowunsupportedsfp=1…
In a home lab with an Aruba S2500 PoE switch and an Intel X520-DA2, three of thirteen cheaply bought Intel AFBR-703SDZ-IN2 SFP+ modules (around 15 USD each) failed within three months: links dropped with dark activity LEDs, two on the switch side and one on the NIC side. Warm and cold reboots…
With two dual-port Mellanox ConnectX-4 cards, a MikroTik SFP+ switch, 1 m OM4 patches and mixed 10G/25G transceivers from several vendors, one NIC port showed link UP but got no DHCP and could not route, 25G transceivers negotiated only 1G, and previously stable 10G links dropped intermittently…
Before deployment the poster asked for a certified or tested SFP28 DAC to connect an HPE FlexFabric 5950 with an SFP28 card to a dual-port Mellanox MCX4121A-ACAT (ConnectX-4 Lx), and for any documentation of that pairing. Hardware involved: HPE FlexFabric 5950, Mellanox MCX4121A-ACAT, SFP28 DAC…
We are handing a 100G circuit off to a core router through a leased optical transport system, and the port on our side refuses to come up. The same pair of modules links instantly on the bench, which is what makes this so irritating. Wedge100BF-32X (wedge100bf32x) running SONiC InnoLight…
Intel-branded servers witth a built-in ConnectX-3 (MT27500, ConnectX3-A1-WSP-QDR, firmware 2.36.5000, mlx4en 4.6, kernel 4.19.68) lost link when a QSFP-to-SFP+ adapter with an SFP+ transceiver replaced direct QSFP cabling: ethtool reported Link detected: no and speed Unknown!, port in ETH moe. The…
Home setup, everything in one rack. I want to connect the NAS to the switch faster than gigabit, but I don't want to run fiber: the distance is about five meters, a plain patch cord covers it. D-Link DGS-1250-28X switch, SFP+ ports free TerraMaster F4-424 Max NAS, copper RJ-45 port short Cat6a…
Small homelab, two second-hand switches and a drawer of optics collected over the years, most of which the hosts refuse because of the vendor code. Recoding has always been the blocker: a proper programmer sits around 369 USD, which is more than I paid for the switches, and the Ubiquiti SFP Wizard…
I do industrial installs, mostly Hirschmann switches in cabinets nobody wants to open twice. On the last couple of projects the optics were the line item that hurt: the switches expect Hirschmann-coded modules, and the original M-SFP parts cost several times an equivalent generic module, with lead…
The poster wanted to use a QSFP+ 40G-to-4x10G breakout cable on a two-port Mellanox ConnectX-3 Pro (MT27520, firmware 2.42.5044, PSID HP1370110017, MLNX OFED 4.6 on Debian 9.6) so each 10G leg could connect to a different switch, similar to what an Intel XL710 offers. SR-IOV virtual functions had…
On Debian 8.11 (kernel 3.16) the poster ran ethtool -m on a Mellanox MT26448 adapter to read optical diagnostics (TX/RX power, temperature, voltage, thresholds) and got Cannot get module EEPROM information: Input/output error. Hardware involved: Mellanox MT26448 ConnectX-2, SFP+ optic with DDM…
I want the ISP box out of the meter cupboard and the GPON line terminated straight on the router. It is a KPN-based line, fibre comes in on SC/APC, and the idea is to move the WAN from the Huawei ONT into the SFP+ cage of the UDM-Pro and keep exactly the VLAN 6 / PPPoE setup the ONT was running…
A DGX Spark with a ConnectX-7 NIC was connected to an existing 10G SFP+ optical network through an inexpensive QSFP-to-SFP+ adapter bought on AliExpress; neither DACs nor standard optical modules produced any link. The poster asked whether the setup could work at all and how to configure it…
We are moving the office uplinks from copper to fibre and the quote that came back has DrayTek-branded optics in every line. Before I start arguing about the difference against ordinary 10G modules I would like to know whether the hardware actually cares what sits in the cage, because the…
I do small business installs, and this one is a fibre service handed off on an ADVA FSP 150-GE102Pro. The customer wants the WAN terminated on their own router instead of the carrier box, so it has to land in the SFP+ cage of a MikroTik RB4011iGS+. Nobody told me what fibre the service actually…
A QSFP112 400G SR4 module in a ConnectX-7 (MCX755106AC-HEAT) with an MPO-12 Type-B cable showed module state Ready and data path DPActivated, but mlxlink --showmodule reported State = Disable, Supported Cable Speed = 0x00000000, Compliance = Unspecified/Undefined, Power Class 1.5 W (too low for…
We are wiring an FPGA capture card into an existing server and I am stuck at the very first step: the port simply never comes up. The setup: Mellanox MCX414-GCAT (ConnectX-4 EN, QSFP28, 50GbE capable) in the host FS Q-8LCA020 breakout AOC, QSFP+ on one end, eight LC ends on the other FPGA card on…
Standing up 25G uplinks from a QFX5120-48Y towards a second switch and a couple of new servers. Before I hand the segment over I want the link settings written down properly, and I cannot find where auto-negotiation lives on these ports. Juniper QFX5120-48Y 25G optics in the SFP28 cages et…
